KiT 6550 Hum

[Mark]

Tim,

It could be the choke, but is could also be the tx vibrating the same area.

A Naim nut friend of mine has tried at least 6 different manufacturer's caps in his pre-amp power supply courtesy of the pins and push fit plugs I soldered on them. I have heard the difference, but it takes me while to work out what the difference is and whether it's better or worse overall. It can affect bass and imaging and transient response or speed. IIRC Naim used to swear by Aerovox in their older kit ?

However, what's more important than the manufacturer is that you buy them from their low ESR (equivalent series resistance) ranges. There are many websites that can explain why better then I can. Here's one :

https://passive-components.eu/why-lo...acitor-design/

"For medium and high voltage applications, low loss aluminum electrolytic capacitors are required. Low ESR capacitors have less power losses and internal heating problems as compared to high ESR capacitors. Apart from lowering performance, high ESR values reduce the life of an aluminum electrolytic capacitor. In addition, a low ESR value allows a greater ripple current capacity to be achieved."

Nichicon and Panasonic and others make low esr caps. Panasonic FM is flavour of the month for some. I have some low esr Nichicon caps in some headphone amps I have. I will check which range they are this evening.

I am sure others on this forum have their favorites.

Mark

[TimN]

Wow! There's more to this than I had realised!

[bob orbell]

Yes, it can become very complicated and can confuse a newcomer, as I said, just replace C1,2,3 & 4 with similar capacitors of 100uF 450volt and C5 which should be no more than 120uf at 500volts, in fact I think it was reduced to 85uF as V1 & 2 did not take too kindly to the larger capacitance. Bob

[Greg.]

Tim, do you have a copy of the build instructions and if not, would you like them? If so, PM me your email address and I will forward.

[TimN]

Thanks very much

[Greg.]

Instructions sent.

[Greg.]

Originally Posted by bob orbell

Any capacitor with 105c deg. rating, all these fancy capacitors are snake oil, try by all means, but you will hear no difference. Bob

It would be helpful, Bob if you could make it clear that this statement is a matter of your opinion and not a matter of fact. Whilst some people might agree with you, others will not. You might not be able to hear a difference between a ‘fancy snake oil capacitor’ and a stock item but I (and I’m sure some others), certainly will hear a difference that might be considered an improvement.

Originally Posted by bob orbell

Yes, it can become very complicated and can confuse a newcomer, as I said, just replace C1,2,3 & 4 with similar capacitors of 100uF 450volt and C5 which should be no more than 120uf at 500volts, in fact I think it was reduced to 85uF as V1 & 2 did not take too kindly to the larger capacitance. Bob

I cannot find anything in the archives that suggest C5 should be reduced to 85uF. If you can evidence this, I’d be grateful for a copy. Of course, what you say may simply be a tweak another owner has carried out and may be recorded somewhere in a thread here, but I don’t recall seeing it. I’d be grateful again if you could post a link if this is the case.

Regarding replacement of C1, 2, 3 & 4, when I worked on Intenso’s 6550, I found the original caps were bulging. His amp also had a buzzing mains transformer and choke. I replaced these with new

https://www.hificollective.co.uk/cat...-hv-axial.html

to very good effect. Not only was the buzz almost completely eradicated, but in our opinion, there was a considerable improvement to the sound quality. Incidentally, the original build recommended mounting C1, 3 & 4 underneath the PSU tag board. I found this is unnecessary and there is sufficient room for all the PSU caps on the top surface which considerably benefits ease of access.

[Mark]

Tim,

It can get as complicated as your time, wallet and ears permit, but I suggest that low esr caps are the best bang for your buck, and buying a selection, burning them in and then doing A/B comparisons is for a dedicated minority.

I have just looked at the schematic for the 6550 and I see that the voltage across C1 and C2 between the rectifier valves and the choke is 475V DC.

Greg has pointed you to the Mundorf caps from Hifi Collective. These are rated to 500V DC and come with his recommendation. It looks like the esr is 0.955 ohm.

Nichicon PW caps are "low esr", I have them in a headphone amp and they are often recommended but I can't find an esr value for comparison on the datasheet and they only do 450V rating.

Personally I would go with Greg's recommendation and spend the time you saved not poring over datasheets listening to music, but someone else on the forum may have an alternative recommendation to Greg's.

Regards

Mark

[vinylspinner]

I remember the amp Tony ( intenso ) had, heard it several times and it sounded very good indeed, the Mundorfs made a very noticeable improvement to the overall performance of the amp. Definitely cheap enough to try out.

Nigel

[bob orbell]

Mark wrote, It can get as complicated as your time, wallet and ears permit, but I suggest that low esr caps are the best bang for your buck, and buying a selection, burning them in. ---- Can you PLEASE explain the part or the capacitor that BURNS, , sorry, but I think it is the most stupid saying of all time in the Hi FI world . Bob